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Matter: Properties & Change

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  1. Matter: Properties & Change Chapter 3

  2. Matter • Matter – anything that has mass and takes up space • Everything around us • Chemistry – the study of matter and the changes it undergoes

  3. Four States of Matter • Solids • particles vibrate but can’t move around • fixed shape • fixed volume • incompressible

  4. Four States of Matter • Liquids • particles can move around but are still close together • variable shape (shape of container) • fixed volume • virtually incompressible

  5. Four States of Matter • Gases • particles can separate and move throughout container • variable shape • variable volume • easily compressed • vapor = gaseous state of a substance that is a liquid or solid at room temperature

  6. Four States of Matter • Plasma • particles collide with enough energy to break into charged particles (+/-) • gas-like, variableshape & volume • stars, fluorescentlight bulbs

  7. Physical Properties • Physical Property can be observed without changing the identity of the substance

  8. Physical Properties • Physical properties can be described as one of 2 types: • Extensive Property depends on the amount of matter present (example: length) • Intensive Property depends on the identity of substance, not the amount (example: density)

  9. Chemical Properties • Chemical Property describes the ability of a substance to undergo changes in identity

  10. Physical vs. Chemical Properties physical chemical physical physical chemical • Examples: • melting point • flammable • density • magnetic • tarnishes in air

  11. Physical Changes • Physical Change • changes the form of a substance without changing its identity • properties remain the same • Examples: cutting a sheet of paper, all phase changes

  12. Phase Changes Evaporation = Condensation = Melting = Freezing = Sublimation = Deposition = Liquid  Gas Gas  Liquid Solid  Liquid Liquid  Solid Solid  Gas Gas  Solid

  13. Chemical Changes • Process that involves one or more substances changing into a new substance • Commonly referred to as a chemical reaction • New substances have different compositions and properties than the original substances

  14. Chemical Changes • Signs of a Chemical Change • change in color or odor • formation of a gas • formation of a precipitate (solid) • change in temperature

  15. Physical vs. Chemical Changes chemical physical chemical physical physical • Examples: • rusting iron • dissolving in water • burning a log • melting ice • grinding spices

  16. Law of Conservation of Mass • Although chemical changes occur, mass is neither created nor destroyed in a chemical reaction • Mass of reactants equals mass of products massreactants = massproducts A + B C

  17. Conservation of Mass • In an experiment, 10.00 g of red mercury (II) oxide powder is placed in an open flask and heated until it is converted to liquid mercury and oxygen gas. The liquid mercury has a mass of 9.26 g. What is the mass of the oxygen formed in the reaction? GIVEN: Mercury (II) oxide  mercury + oxygen mmercury(II) oxide = 10.00 g mmercury = 9.86 g moxygen = ? WORK: 10.00 g = 9.86 g + moxygen moxygen = (10.00 g – 9.86 g) moxygen = 0.74 g Mercury (II) oxide  mercury + oxygen Mmercury(II) oxide = 10.00 g Mmercury = 9.26 Moxygen = ? massreactants = massproducts

  18. MIXTURE PURE SUBSTANCE yes no yes no Is the composition uniform? Can it be chemically decomposed? Matter Flowchart MATTER yes no Can it be physically separated? Homogeneous Mixture (solution) Heterogeneous Mixture Compound Element

  19. Matter Flowchart element heterogeneous mixture compound heterogeneous mixture solution • Examples: • graphite • pepper • sugar (sucrose) • paint • soda

  20. Pure Substances • Element • composed of identical atoms • Example: copper wire, aluminum foil

  21. Pure Substances • Compound • composed of 2 or more elements in a fixed ratio • properties differ from those of individual elements • Example: table salt (NaCl)

  22. Mixtures • Variable combination of 2 or more pure substances. Heterogeneous Homogeneous

  23. Mixtures • Solution • homogeneous • very small particles • particles don’t settle • Example: rubbing alcohol

  24. Mixtures • Heterogeneous • medium-sized to large-sized particles • particles may or may not settle • Example: milk, fresh-squeezed lemonade

  25. Mixtures • Examples: • tea • muddy water • fog • NaCl & H2O • Italian salad dressing • Answers: • Solution • Heterogeneous • Heterogeneous • Solution • Heterogeneous

  26. Separating Mixtures • Substances in a mixture are physically combined, so processes bases on differences in physical properties are used to separate components • Numerous techniques have been developed to separate mixtures to study components • Filtration • Distillation • Sublimation • Crystallization • Chromatography

  27. Filtration • Used to separate heterogeneous mixtures composed of solids and liquids • Uses a porous barrier to separate the solid from the liquid • Liquid passes through leaving the solid in the filter paper

  28. Distillation • Used to separate homogeneous mixtures • Based on differences in boiling points of substances involved

  29. Sublimation Process during which a solid changes to a vapor without melting Can be used to separate two solids present in a mixture when one of the solids sublimates but the other does not

  30. Crystallization • Separation technique that results in the formation of pure solid particles from a solution containing the dissolved substance • As one substance evaporates, the dissolved substance comes out of solution and collects as crystals • Produces highly pure solids • Rocky candy is an example of this

  31. Chromatography • Separates components of a mixture based on ability of each component to be drawn across the surface of another material • Mixture is usually liquid and is usually drawn across chromatography paper • Separation occurs because various components travel at different rates • Components with strongest attraction for paper travel the slowest; components with strongest attraction for the liquid travel the fastest

  32. Separation of a CompoundThe Electrolysis of Water Compounds must be separated by chemical means. With the application of electricity, water can be separated into its elements Reactant  Products Water  Hydrogen + Oxygen 2 H2O  2 H2 + O2